The present invention relates generally to die casting and more specifically to an apparatus in which a mold opening/closing unit is mounted on a carrier and is freely moved in/out from a mold clamping unit.
In a conventional die casting apparatus, a pair of metal molds are clamped by a mold clamping unit to perform casting. However, recently, in order to reduce the duration of a casting cycle, a continuous die casting apparatus has been developed in which a plurality of mold opening/closing units, each comprising metal molds and a temporary mold clamping mechanism, are sequentially moved in/out from a main mold clamping/casting unit, for casting after clamping. In an example apparatus of this type, mold opening/closing units are moved into and out of a mold clamping unit alternately from both the right and left sides thereof as disclosed in Japanese Utility Model Laid-Open (Kokai) No. 58-9725. In an example rotary die casting machine, a plurality of mold opening/closing units are moved in respective holding portions formed on a rotary table which rotates so that the mold opening/closing units are sequentially positioned at a mold clamping station to perform mold clamping and casting as disclosed in Japanese Patent Laid-Open (Kokai) No. 61-195766 also filed by the present applicant.
The former apparatus, in which the mold opening/closing units are moved into and out of the mold clamping unit alternately from the right and left sides thereof, includes a long carrier extending from a mold clamping position to one mold opening/closing position and two mold opening/closing units mounted on the long carrier. The carrier is reciprocated rightward and leftward so that when one mold opening/closing unit is located at the mold clamping position, the other mold opening/closing unit is located at an external mold opening/closing position. As a result, while casting is being performed to one mold opening/closing unit, the other mold opening/closing unit is being prepared.
In the latter rotary die casting machine, the mold opening/closing units are located on rollers of a metal mold setting unit and sequentially moved onto rollers of the holding portions on the rotary table. Each mold opening/closing unit is floated from the corresponding roller by a cylinder provided at the holding portion for temporarily clamping the molds. Then, the rotary table is rotated to move each mold opening/closing unit to the mold clamping/casting position for performance of final mold clamping and casting.
Of the above conventional die casting apparatuses, in the former apparatus in which the mold opening/closing units are moved in the mold clamping unit alternately from both the right and left sides thereof, two mold opening/closing units are mounted on a single carrier. Therefore, if one of the mold opening/closing units malfunctions and needs repair, the carrier cannot be moved until repair is completed, meanwhile interrupting production of the other mold opening/closing unit.
In the latter rotary die casting machine, each mold Opening/closing unit is directly moved onto the roller of the corresponding holding portion without a carrier. Therefore, a cylinder for floating the mold opening/closing units must be provided at each holding portion, complicating the structure.